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30 Cards in this Set

  • Front
  • Back
Which of the following viruses is the most common cause of winter viral encephalitis?
A. lymphocytic choriomeningitis virus
B. Coxsackie A virus
C. Coxsackie B virus
D. human herpes virus 6
E. West Nile virus
A. lymphocytic choriomeningitis virus.
LCMV is the most common cause of winter/spring viral encephalitis, while enteroviruses such as Coxsackie, are the main causes of summer/fall epidemics. LCMV is
spread to humans through contact with infected mouse feces.
QCCP2, Meningitis, specific agents
Which feature separates the typeable from non-typeable strains of Haemophilus influenzae?
A. HA antigen
B. capsule
C. mecA gene
D. penicillin binding protein
E. growth at 42°C
B. capsule.
The presence of a capsule separates the typeable (capsulated) from the non-typeable (unencapsulated). Furthermore, the typeable strains are categorized into serotypes
according to the type of capsule protein present - the most prevalent serotype being type B.
QCCP2, Meningitis, specific agents
Patients with complement deficiencies are at an increased risk for meningitis caused by this infectious agent:
A. Streptococcus pneumoniae
B. Haemophilus influenzae
C. E. coli
D. Listeria monocytogenes
E. Neisseria meningitidis
E. N.
N. meningitidis is associated with outbreaks of meningitis in children and adults in close living conditions, such as schools, dorms, barracks, or nursing homes (though
less prevalent in the elderly). Systemic meningococcemia is associated with a petechial rash and hemorrhagic adrenal infarction (Waterhouse-Friedrichsen syndrome),
both of which have a poor prognosis.
QCCP2, Meningitis, specific agents
Which of the following organisms typically causes meningitis in a disproportionate number of both very young and very old patients?
A. group B Streptococcus
B. Staphylococcus aureus
C. Listeria monocytogenes
D. Streptococcus pneumoniae
E. Haemophilus influenzae
C. L.
Besides age (<1 month and older than 70 years), predisposing factors toward the development of Listeria meningitis include diabetes and immunosuppression (steroids,
HIV, and transplantation).
QCCP2, Meningitis, specific agents
Which of the following amoebae is most commonly the cause of primary amebic encephalitis?
A. Entamoeba histolytica
B. Acanthamoeba
C. Entamoeba coli
D. Endolimax nana
E. Naegleria fowleri
E. N.
Naegleria infection is associated with fresh water exposure. The organism migrates through the nasopharynx and invades the brain through the cribriform sinus. Often
there is a history of trauma in fresh water (water skiing accident, diving accident). The infection is especially virulent, often causing death within days. Acanthamoeba
can also cause encephalitis, but with a granulomatous appearance. Acanthamoeba is also responsible for the majority of cases of amebic keratitis.
QCCP2, Meningitis, specific agents
Which of the following etiologies of meningitis is consistent with CSF findings of glucose <45 mg/dL, protein >500 mg/dL, and a white blood cell count >1000
WBC/mL?
A. viral
B. amebic
C. aseptic
D. bacterial
E. chemical
D. bacterial.
The cause of meningitis can be narrowed down with the CSF chemistry. Low glucose and high protein/WBC count is consistent with a bacterial meningitis. The WBC
differential is typically left-shifted with a predominance of neutrophils.
QCCP2, Laboratory evaluation
Latex agglutination tests on CSF are commonly used for the diagnosis of all of the following causes of meningitis, except:
A. Haemophilus influenzae, type B
B. Neisseria meningitidis
C. group B Streptococcus
D. Listeria monocytogenes
E. Streptococcus pneumoniae
D. L.
Listeria is a very difficult organism to identify in CSF. Gram stain sensitivity is less than 50% and there is no commercially available latex agglutination test at this time.
Culture is the main source of positive identification.
QCCP2, Laboratory evaluation
All of the following criteria are used in the diagnosis of prosthetic joint infection, except:
A. joint pain with positive bacteremia in two successive blood cultures
B. growth of the same microorganism in two or more synovial fluid or periprosthetic tissue cultures
C. purulent synovial fluid or periprosthetic tissue
D. acute inflammation in periprosthetic tissue
E. presence of a sinus tract
A. joint pain with positive bacteremia in 2 successive blood cultures.
Each of the applicable criteria is fairly specific for prosthetic joint infection. There are several etiologies of joint infection. The most common is the direct introduction of
bacteria, though in a small percentage of late infection, hematogenous spread is the cause.
QCCP2, Prosthetic joint infection and other clinical syndromes
What is/are the most common bacterium found in prosthetic joint infections?
A. Staphylococcus aureus
B. Staphylococcus epidermidis
C. Streptococci spp
D. gram negative bacilli
E. Enterococcus
B. S.
Coagulase-negative staph account for almost 1/2 of the cases of prosthetic joint infections, most often presenting months after surgery. This makes sense since coagnegative
staph is a normal skin flora microbe and the majority of joint infections are due to the introduction of bacteria during surgery. On the other hand, since it is
normal skin flora, coag-negative staph is a common cause of contamination of cultures.
QCCP2, Prosthetic joint infections and other clinical syndromes
What is the causative agent of visceral larva migrans?
A. Ancylostoma brazilensis
B. Loa loa
C. Toxicara canis
D. Francisella tularensis
E. Chlamydia trachomatis
C. T.
Ancylostoma is the causative agent of cutaneous larval migrans, while Loa loa inhabits the subcutis and conjunctiva. Francisella tularensis causes ulceroglandular fever.
Chlamydia trachomatis causes lymphogranuloma venereum and trachoma.
QCCP2, T3.2
What is the overall most common cause of bacterial cellulitis?
A. coagulase-negative Staphylococcus
B. group A Streptococcus
C. Pasteurella multocida
D. Aeromonas hydrophila
E. Vibrio vulnificus
B. group A S
Coag-negative strep causes many cases of post-traumatic cellulitis; Pasteurella is associated with animal bites, Aeromonas with fresh water and V. vulnificus with salt
water exposure.
QCCP2, T3.2
Which of the following organisms is the most common cause viral myocarditis?
A. adenovirus
B. JC virus
C. Coxsackie A
D. Coxsackie B
E. human herpes virus 6
D. Coxsackie B.
Coxsackie A and B are frequently confused for each other when it comes to the diseases that they each cause. Coxsackie A causes hand-foot-mouth disease, so named
for the most common locations of the lesions. Coxsackie B, on the other hand, is responsible for the majority of cases of viral myocarditis.
QCCP2, T3.2
All of the following viruses are most commonly detected by culture, except:
A. HSV-1
B. HSV-2
C. adenovirus
D. HPV
E. EBV
E. EBV.
EBV, along with rubella and the arboviridae, are not routinely cultured, but rather diagnosed based on the positive serology. Similarly, rota- and rhabdoviruses are not
cultured; their diagnosis depends on virus-specific antigen detection.
QCCP2, Virology Laboratory Methods
MRC-5 cells are an example of which kind of cell culture?
A. primary cell culture
B. cell line (secondary cell culture)
C. established cell line
D. human diploid fibroblast
E. malignant transformed cell line
B. cell line (secondary cell culture).
MRC-5, named for the Medical Research Council where they were first propagated, are a secondary cell line with limited viability. Cells don't survive after a number of
transfers, unlike a primary cell culture, which can't be transferred at all, or an established cell line, which can be transferred nearly illimitably. Human diploid fibroblasts
are another type of secondary cell culture.
QCCP2, Viral lab methods
All of the following organisms utilize the mosquito as a vector, except:
A. Loa loa
B. Wuchereria bancrofti
C. Brugia malayi
D. Dirofilaria immitis
E. Plasmodium falciparum
A. L.
Loa loa is spread by the mango fly (Chrysops). There are a few memorable and significant vector-organism pairs to remember. Lyme disease, ehrlichiosis, and babesiosis
are spread by the Ixodes tick. Borrelia recurrentis is the only borrelial species spread by a louse (the human body louse) rather than a tick. Trypanosoma cruzi and the
reduviid bug, Leishmania (cutaneous) and the sandfly (Phlebotomus), and Onchocerca and the black fly (Simulium) are all high-yield.
QCCP2, T3.3, Vectors
Which of the following viruses grows best in Hep2 cells?
A. enterovirus
B. Coxsackie A
C. Coxsackie B
D. adenovirus
E. cytomegalovirus
D. adenovirus.
Hep2 cells are derived from the upper respiratory tract, a region for which adenovirus has a high tropism (same with RSV).
QCCP2, T3.4
What's the most common cause of false positive hemadsorption in viral culture?
A. Mycoplasma spp
B. simian virus
C. mycobacterium
D. Acanthamoeba
E. Candida
B. simian virus.
SV is a very common cause of false positive hemabsorption results. An uninoculated control should be run concurrent with the patient sample as a negative control.
Another common contaminant is Mycoplasma, which can cause poor growth in cell lines and decreased infective potential of the viruses.
QCCP2, Virology, lab methods
Which of the following viruses is assayed by injection into suckling mice and observation for flaccid paralysis?
A. Clostridium botulinum
B. adenovirus
C. parvovirus
D. Coxsackie A virus
E. respiratory syncytial virus
D. Coxsackie A virus.
Clostridium botulinum can cause flaccid paralysis in infants, but it's not a virus, and it's not assayed in suckling mice. Adenovirus causes cytopathic effect in Hep2 cells,
parvovirus needs erythroid precursors and RSV causes syncytia formation in Hep2 cells.
QCCP2, T3.5
Which of the following viruses causes syncytia formation in culture?
A. RSV
B. measles
C. HSV
D. A & B
E. A, B, C
E. A, B, C.
If you think about the histopathology of these viruses, it helps. RSV of course causes syncytia formation - it's in the name! Measles infection can cause the formation of
Warthin-Finkeldey giant cells, and then there's the 3 Ms describing the nuclei of cells infected with HSV - multinucleation, margination, and molding.
QCCP2, T3.6, viral histology
Which of the following viruses can have both nuclear and cytoplasmic inclusions?
A. CMV
B. measles
C. rabies
D. A & B
E. A, B, C
D. A & B.
Both CMV and measles are known for having nuclear and cytoplasmic inclusions. HSV and adenovirus have nuclear inclusions only, while rabies is the only major human
viral pathogen with cytoplasmic inclusions only (Negri bodies).
QCCP2, T3.6, Viral histology
What magnitude elevation of virus-specific IgG titer is usually considered the minimum for the diagnosis of an acute viral infection?
A. 2 fold
B. 4 fold
C. 10 fold
D. 100 fold
E. 1 million billion fold
B. 4 fold.
Paired sera collected 7-10 days apart is used to measure the elevation of IgG titers between convalescence and acute illness. Elevation of 4-fold is considered strong
evidence for an acute infection, while a single elevated IgM titer has similar connotations.
QCCP2, Virology, laboratory evaluation
Which of the following herpes virus family members lie latent in the dorsal root ganglia?
A. HSV-1
B. HSV-2
C. VZV
D. A & B
E. A, B, C
E. A, B, C.
The HSV family of viruses is made up of the prototypical enveloped DNA viruses. Three of the members lie dormant within dorsal root ganglia until they are reactivated.
QCCP2, Human herpes viruses, T3.8
Why is caesarean section delivery of children from mothers with prodromal or active genital herpes recommended?
A. increased risk of vaginal trauma to the mother
B. indication of immunodeficiency in mother and increased risk of secondary infection
C. to decrease the risk of neonatal herpes
D. to decrease the risk of spreading infection to health care workers
E. to decrease risk of puerperal coinfection
C. to decrease the risk of neonatal herpes.
Vertical transmission of HSV from genital lesions to an infant can cause neonatal HSV infection, which can manifest as skin lesions to encephalitis, retinitis, even sepsis.
There is a very high transmission rate with vaginal birth.
QCCP2, Human herpes viruses
How can herpes simplex virus definitively be identified in shell vial assay?
A. direct fluorescent antibody stain
B. cytopathic effect viewed with light microscopy
C. reculture (shell vial assay as a starter culture)
D. A & B
E. A, B, C
A. direct fluorescent antibody stain.
The shell vial technique is very popular in virus labs due to its small size, low volume, ease of use, and ability to run multiple samples in parallel. The assay involves
centrifugation of the patient sample onto a cover slip coated with a culture monolayer. In a shell vial assay for HSV, cytopathic effect is NOT used as indication of a
positive assay, but rather the detection of viral antigens by direct fluorescent antibody staining.
QCCP2, Human herpes virus
All of the following features are used to diagnose congenital varicella, except:
A. maternal VZV during pregnancy
B. skin lesions in newborn in a dermatomal distribution
C. serological evidence of newborn infection with elevated specific IgG persisting beyond 7 months
D. serological evidence of newborn infection with elevated specific IgM
E. all of the above are potentially utilized in the diagnosis of congenital varicella
E. All of the above are potentially utilized in the diagnosis of congenital varicella.
The incidence of perinatal varicella is highest when the mother contracts VZV within a few days of delivery, with the incidence declining inversely with gestational age.
Because of the extremely high infectivity of VZV contracted perinatally (50-60%), VZ immunoglobulin is recommended for prophylaxis, perhaps along with acyclovir.
QCCP2, VZV
Ramsay-Hunt syndrome is an infection of the facial nerve as caused by which of the following viruses?
A. SV40
B. CMV
C. HSV
D. VZV
E. HIV
D. VZV.
VZV reactivation in a dermatomal pattern is the cause of the painful shingles rash. When reactivation occurs in the facial nerve the Ramsay-Hunt syndrome can result in
facial paralysis, vertigo, tinnitus, and otalgia.
QCCP2, VZV
In which of the following patient populations is the risk of CMV retinitis, encephalitis, or nephritis at its highest?
A. HIV patients with a CD4 counts <100/mL
B. HIV patients with CD4 counts between 500 and 1000/mL
C. solid-organ transplant recipients
D. older children
E. elderly adults
A. HIV patients with CD4 counts <100/mL.
In addition to HIV patients with very low CD4 counts, immunocompromised transplant recipients are at an increased risk, though not as great as that of HIV patients.
Typically, primary CMV presents with a mononucleosis-like syndrome, which can progress to a pneumonia - especially in neonates and the immunocompromised.
QCCP2, CMV
Which of the following viruses is responsible for the most common congenital infection in the United States?
A. VZV
B. CMV
C. parvovirus B19
D. EBV
E. adenovirus
B. CMV.
Passed transplacentally, the risk of in utero infection is greatest when the mother acquires a primary CMV infection while pregnant. The effects from in utero infection
can range from severe to mild, with the most common manifestation of sensorineural hearing loss.
QCCP2, CMV
All of the following factors affect the rate of CMV seropositivity?
A. pregnancy status
B. locale
C. age
D. socioeconomic status
E. all of the above affect the seropositivity rate
A. pregnancy status.
While the effects of primary and reactivated CMV infection in pregnant women are potentially dire, there is no statistically significant effect on the rate of seropositivity. The
rate of seropositivity in Africa is much greater than most of the rest of the world. The risk of CMV infection increases with age (presumably due to increased risk of
exposure). Also, lower socioeconomic status is associated with increased CMV seropositivity.
QCCP2, CMV
All of the following techniques are routinely used to diagnose CMV, except:
A. culture
B. PCR
C. flaccid paralysis in suckling mice injected with patient serum
D. direct fluorescent antibody
E. serology
C. flaccid paralysis in suckling mice after injection.
In addition to tissue histology looking for the characteristic nuclear owl eye, inclusions can be performed if diagnostic tissue is available. Observation of flaccid paralysis in
suckling mice is used to diagnose Coxsackie A virus.
QCCP2, CMV